Irradiation is in progress. Radiation therapy (radiotherapy) - contraindications, consequences and complications. Methods for restoring the body after radiation therapy. Potential risks of radiation therapy

Radiation therapy: what it is and what are the consequences - a question that interests people who are faced with cancer problems.

Radiation therapy in oncology has become a fairly effective tool in the fight for human life and is widely used throughout the world. Medical centers providing such services are highly rated by specialists. Radiation therapy is carried out in Moscow and other cities of Russia. Often this technology allows you to completely eliminate a malignant tumor, and in severe forms of the disease - to prolong the patient's life.

What is the essence of technology

Radiation therapy (or radiotherapy) is the effect of ionizing radiation on the site of tissue damage in order to suppress the activity of pathogenic cells. Such exposure can be done using X-ray and neutron radiation, gamma radiation or beta radiation. A directed beam of elementary particles is provided by special medical-type accelerators.

During radiation therapy, there is no direct disintegration of the cellular structure, but a change in DNA is provided, which stops cell division. The impact is aimed at breaking molecular bonds as a result of ionization and radiolysis of water. Malignant cells are distinguished by their ability to rapidly divide and are extremely active. As a result, it is these cells, as the most active, that are exposed to the action of ionizing radiation, and the normal cellular structures do not change.

Strengthening the impact is also achieved by different directions of radiation, which allows you to create maximum doses in the lesion focus. Such treatment is most widespread in the field of oncology, where it can act as an independent method or supplement surgical and chemotherapy methods. For example, radiation therapy of blood for various types of its lesions, radiation therapy for breast cancer or radiation therapy of the head show very good results at the initial stage of pathology and effectively destroy the remnants of cells after surgery at later stages. A particularly important area of ​​radiotherapy is the prevention of cancer metastasis.

Often, this type of treatment is also used to combat other types of pathologies not related to oncology. So radiotherapy shows high efficiency in eliminating bone growths on the legs. X-ray therapy is widely used. In particular, such radiation helps in the treatment of hypertrophic sweating.

Features of the implementation of treatment

The main source of directed particle flux for performing medical tasks is a linear accelerator - radiation therapy is carried out with the appropriate equipment. The treatment technology provides for a stationary position of the patient in a supine position and a smooth movement of the beam source along the marked lesion. This technique makes it possible to direct the flow of elementary particles at different angles and with different radiation doses, while all movements of the source are controlled by a computer according to a given program.

The irradiation regimen, the therapy regimen and the duration of the course depend on the type, location and stage of the malignant neoplasm. As a rule, the course of treatment lasts 2-4 weeks with the procedure being carried out 3-5 days a week. The duration of the radiation session itself is 12-25 minutes. In some cases, a one-time exposure is prescribed to relieve pain or other manifestations of advanced cancer.

According to the method of supplying the beam to the affected tissues, surface (remote) and interstitial (contact) effects are distinguished. Remote irradiation consists of placing the beam sources on the surface of the body. In this case, the flow of particles is forced to pass through the layer of healthy cells and only then focus on malignant formations. With this in mind, when using this method, various side effects occur, but, despite this, it is the most common.

The contact method is based on the introduction of a source into the body, namely in the area of ​​the lesion focus. This version uses devices in the form of a needle, wire, capsule. They can be inserted only for the duration of the procedure or implanted for a long time. With the contact method of exposure, a beam directed strictly at the tumor is provided, which reduces the effect on healthy cells. However, in terms of the degree of trauma, it surpasses the surface method, and also requires special equipment.

What types of rays can be used

Different types of ionizing radiation can be used depending on the task of radiation therapy:

1. Alpha radiation. In addition to the flux of alpha particles obtained in a linear accelerator, various techniques are used based on the introduction of isotopes that can be removed from the body quite simply and quickly. The most widely used are radon and thoron products, which have a short life span. Among the various techniques, the following stand out: radon baths, the use of water with radon isotopes, microclysters, inhalation of aerosols with saturation of isotopes, the use of dressings with radioactive impregnation. Find uses of thorium-based ointments and solutions. These treatments are used in the treatment of cardiovascular, neurogenic and endocrine pathologies. Contraindicated in tuberculosis and for pregnant women.

2. Beta radiation. To obtain a directed stream of beta particles, appropriate isotopes are used, for example, isotopes of yttrium, phosphorus, thallium. Sources of beta radiation are effective with the contact method of exposure (interstitial or intracavitary), as well as with the imposition of radioactive applications. So applicators can be used for capillary angiomas and a number of eye diseases. Colloidal solutions based on radioactive isotopes of silver, gold and yttrium, as well as rods up to 5 mm long from these isotopes, are used for contact action on malignant tumors. This method is most widely used in the treatment of oncology in the abdominal cavity and pleura.

3. Gamma radiation. This type of radiation therapy can be based on both the contact method and the remote method. In addition, a variant of intense radiation is used: the so-called gamma knife. The source of gamma particles is the isotope of cobalt.

4. X-ray radiation. X-ray sources with a power from 12 to 220 keV are intended for the implementation of the therapeutic effect. Accordingly, with an increase in the power of the emitter, the depth of penetration of the rays into the tissues increases. X-ray sources with an energy of 12-55 keV are aimed at working from short distances (up to 8 cm), and the treatment covers the superficial skin and mucous layers. Long-distance distance therapy (distance up to 65 cm) is carried out with an increase in power up to 150-220 keV. Remote exposure of medium power is intended, as a rule, for pathologies not related to oncology.

5. Neutron radiation. The method is carried out using special neutron sources. A feature of such radiation is the ability to combine with atomic nuclei and the subsequent emission of quanta that have a biological effect. Neutron therapy can also be used in the form of remote and contact effects. This technology is considered the most promising in the treatment of extensive tumors of the head, neck, salivary glands, sarcoma, tumors with active metastasis.

6. Proton radiation. This option is based on the remote action of protons with energies up to 800 MeV (for which synchrophasotrons are used). The proton flux has a unique dose gradation with respect to the penetration depth. Such therapy makes it possible to treat very small lesions, which is important in ophthalmic oncology and neurosurgery.

7. Pi-meson technology. This method is the latest in medicine. It is based on the emission of negatively charged pi-mesons produced by unique equipment. This method has so far been mastered only in a few of the most developed countries.

Than radiation exposure threatens

Radiation therapy, especially its distant form, leads to a number of side effects, which, given the danger of the underlying disease, are perceived as inevitable, but a minor evil. The following are characteristic consequences of radiation therapy for cancer:

1. When working with the head and in the neck area: causes a feeling of heaviness in the head, hair loss, hearing problems.
2. Treatments on the face and in the cervical area: dry mouth, discomfort in the throat, pain symptoms during swallowing movements, loss of appetite, hoarseness in the voice.
3. Exercise on the organs of the thoracic region: dry type cough, shortness of breath, muscle pain and pain symptoms during swallowing movements.
4. Treatment in the breast area: swelling and pain in the gland, skin irritation, muscle pain, cough, throat problems.
5. Procedures on organs related to the abdominal cavity: weight loss, nausea, vomiting, diarrhea, pain in the abdominal area, loss of appetite.
6. Treatment of the pelvic organs: diarrhea, urinary disorders, vaginal dryness, vaginal discharge, pain in the rectum, loss of appetite.

What to consider during the course of treatment

As a rule, when carrying out radiation exposure in the zone of contact with the emitter, skin disorders are observed: dryness, peeling, redness, itching, rash in the form of small papules. To eliminate this phenomenon, external agents are recommended, for example, Panthenol aerosol. Many body responses become less pronounced when nutrition is optimized. It is recommended to exclude hot seasonings, pickles, sour and rough foods from the diet. Emphasis should be placed on steam-based foods, cooked foods, and chopped or pureed ingredients.

The diet should be set in frequent and fractional (small doses). You need to increase your fluid intake. To reduce the manifestations of problems in the throat, you can use a decoction of chamomile, calendula, mint; bury sea buckthorn oil in the nasal sinuses, consume vegetable oil on an empty stomach (1-2 tablespoons).

Probably, there is no worse disease today than cancer. This ailment does not look at either age or status. He mercilessly mows down everyone. Modern methods of treating tumors are quite effective if the disease was detected in the early stages. However, cancer treatment also has a negative side. For example, radiation therapy, the side effects of which sometimes have high health risks.

Benign and malignant tumors

A tumor is a pathological formation in tissues and organs that grows rapidly, causing fatal harm to organs and tissues. All neoplasms can be roughly divided into benign and malignant.

Cells of benign tumors differ little from healthy cells. They grow slowly and do not spread beyond their focus. It is much easier and easier to treat them. They are not fatal to the body.

The cells of malignant neoplasms are structurally unlike normal healthy cells. Cancer grows rapidly, affecting other organs and tissues (metastasizes).

Benign tumors do not cause much discomfort to the patient. Malignant ones are accompanied by pain and general exhaustion of the body. The patient loses weight, appetite, interest in life.

Cancer develops in stages. The first and second stages have the most favorable prognosis. The third and fourth stages are the growth of the tumor into other organs and tissues, that is, the formation of metastases. Treatment at this stage is aimed at pain relief and prolongation of the patient's life.

No one is immune from such a disease as cancer. People at particular risk are:

With a genetic predisposition.

Immunocompromised.

Leading the wrong lifestyle.

Working in hazardous working conditions.

Those who have received any mechanical injuries.

For prevention purposes, you need to be examined by a therapist once a year and be tested. For those at risk, it is advisable to donate blood for tumor markers. This test helps to recognize cancer in its early stages.

How is cancer treated?

There are several ways to treat malignant tumors:

Surgery. The main method. It is used in cases where oncology is not yet large enough, as well as when there are no metastases (early stages of the disease). Radiation or chemotherapy can be done beforehand.

Radiation therapy of tumors. Irradiation of cancer cells using a special device. This method is used both independently and in combination with other methods.

Chemotherapy. Treating cancer with chemicals. It is used in combination with radiation therapy or surgery to reduce the size of a mass. It is also used to prevent metastasis.

Hormone therapy. Used to treat ovarian, breast and thyroid cancers.



The most effective today is the surgical treatment of tumors. The operation has the least number of side effects and gives the patient more chances for a healthy life. However, the application of the method is not always possible. In such cases, other methods of treatment are used. The most common of which is radiation therapy. Although the side effects after it cause a lot of health problems, the patient's chances of recovery are high.

Radiation therapy

It is also called radiation therapy. The method is based on the use of ionizing radiation, which absorbs the tumor and self-destructs. Unfortunately, not all cancers are sensitive to radiation. Therefore, the choice of the method of therapy should be after a thorough examination and assessment of all risks to the patient.

Radiation therapy, although effective, has a number of side effects. The main one is the destruction of healthy tissues and cells. Radiation affects not only the tumor, but also the neighboring organs. A method of radiation therapy is prescribed in cases where the benefit to the patient is high.



Radium, cobalt, iridium, cesium are used for radiation. Doses of radiation are compiled individually and depend on the characteristics of the tumor.

How is radiation therapy done?

Radiotherapy can be done in several ways:

1. Irradiation at a distance.

   Contact irradiation.

   Intracavitary irradiation (a radioactive source is introduced into an organ with a neoplasm).

   Interstitial irradiation (a radioactive source is injected into the tumor itself).

Radiation therapy is used:

after surgery (to remove the remnants of cancer);

before surgery (to reduce the size of the tumor);

during the development of metastases;

with relapses of the disease.

Thus, the method has three purposes:

Radical - complete removal of the tumor.

Palliative - a decrease in neoplasm in size.

Symptomatic - elimination of pain symptoms.



Radiation therapy can heal many cancers. With its help, you can alleviate the suffering of the patient. And also to prolong his life when healing is impossible. For example, radiation therapy to the brain provides the patient with legal capacity, relieves pain and other unpleasant symptoms.

For whom is irradiation contraindicated?

As a cancer-fighting method, radiation therapy is not for everyone. It is prescribed only in cases where the benefit to the patient is higher than the risk of complications. For a separate group of people, radiotherapy is generally contraindicated. These include patients who:

Severe anemia, cachexia (a sharp breakdown and exhaustion).

There are diseases of the heart, blood vessels.

Radiation therapy of the lungs is contraindicated for cancerous pleurisy.

There is renal failure, diabetes mellitus.

There are bleeding associated with the tumor.

There are multiple metastases with deep penetration into organs and tissues.

The blood contains a low number of leukocytes and platelets.

Radiation intolerance (radiation sickness).

For such patients, the course of radiation therapy is replaced by other methods - chemotherapy, surgery (if possible).



It should be noted that those who are indicated for radiation may subsequently suffer from its side effects. Since ionizing rays damage not only the structure but also healthy cells.

Side effects of radiation therapy

Radiation therapy is the strongest exposure of the body to radioactive substances. In addition to being very effective in fighting cancer, this method has a whole bunch of side effects.

Patient reviews of radiation therapy are very different. Some have side effects after just a few procedures, while others have practically no side effects. One way or another, any unpleasant phenomena will disappear after the end of the course of radiotherapy.

The most common consequences of the method:

Weakness, headache, dizziness, chills, increased

Disrupted work of the digestive system - nausea, diarrhea, constipation, vomiting.

Change in blood composition, decrease in platelets and leukocytes.

An increased number of heartbeats.

Swelling, dry skin, rashes in the places where radiation is applied.

Hair loss, hearing loss, vision loss.

Minor blood loss, provoked by vascular fragility.

This is with regard to the main negative points. After radiation therapy (complete completion of the course), the work of all organs and systems is restored.

Nutrition and renewal of the body after irradiation

During the treatment of tumors, no matter what method, it is necessary to eat properly and balanced. In this way, many unpleasant symptoms of the disease (nausea and vomiting) can be avoided, especially if a course of radiation therapy or chemistry is prescribed.

Food should be taken frequently and in small portions.

Food should be varied, rich and fortified.

For a while, you should give up food that contains preservatives, as well as salty, smoked and fatty foods.

It is necessary to limit the use of dairy products due to possible lactose intolerance.

Carbonated and alcoholic drinks are prohibited.

Preference should be given to fresh vegetables and fruits.

In addition to proper nutrition, the patient should adhere to the following rules:

Get more rest, especially after the radiation procedures themselves.

Do not take a hot bath, do not use hard sponges, toothbrushes, decorative cosmetics.

Spend more time outdoors.

Lead a healthy lifestyle.



Patient reviews of radiation therapy are very different. However, without it, successful cancer treatment is impossible. By adhering to simple rules, many unpleasant consequences can be avoided.

For what diseases is LT being prescribed?

Radiation therapy is widely used in medicine to treat cancer and several other diseases. depends on the severity of the disease and can be broken down into a week or more. One session lasts from 1 to 5 minutes. Used in the fight against tumors that do not contain fluid or cysts (skin cancer, cancer of the cervix, prostate and breast, brain, lung, as well as leukemia and lymphomas).

Most often, radiation therapy is prescribed after surgery or before it in order to reduce the size of the tumor, as well as kill the remnants of cancer cells. In addition to malignant tumors, diseases of the nervous system, bones and some others are also treated with the help of radio waves. The radiation doses in such cases differ from the oncological doses.

Repeated radiation therapy

Irradiation of cancer cells is accompanied by simultaneous irradiation of healthy cells. Side effects after RT are not pleasant phenomena. Of course, after canceling the course, after a while the body is restored. However, having received a single dose of radiation, healthy tissues are not able to withstand repeated radiation. In the case of using radiotherapy a second time, it is possible in emergency cases and with lower doses. The procedure is prescribed when the benefits to the patient outweigh the risks and complications to his health.



If re-exposure is contraindicated, an oncologist may prescribe hormone therapy or chemotherapy.

Radiation therapy for advanced cancer

The method of radiotherapy is used not only to treat cancers, but also to prolong the life of a patient in the last stages of cancer, as well as to alleviate the symptoms of the disease.

When a tumor spreads to other tissues and organs (metastasizes), there is no chance of recovery. The only thing that remains is to accept and wait for that “doomsday”. In this case, radiation therapy:

Reduces and sometimes completely relieves pain attacks.

Reduces pressure on the nervous system, on bones, and maintains capacity for action.

Reduces blood loss, if any.

Irradiation for metastases is prescribed only at the sites of their spread. It should be remembered that radiation therapy has a wide variety of side effects. Therefore, if the patient has a sharp depletion of the body and he cannot withstand the radiation dose, this method is not practiced.

Conclusion

The worst disease is cancer. The whole insidiousness of the disease is that it may not manifest itself in any way for many years and in just a couple of months bring a person to death. Therefore, for the purpose of prevention, it is important to periodically be examined by a specialist. Detection of an ailment in the early stages always ends with complete healing. One of the most effective methods of fighting cancer is radiation therapy. Side effects, although unpleasant, however, completely disappear after the course is canceled.

Radiotherapy used in advanced gastric cancer as a method to relieve obstruction symptoms. In addition, radiation therapy can stop bleeding from a cancer in inoperable cases. Radiotherapy is given every day for 5 minutes for 2-5 weeks. In this case, temporary loss of appetite, nausea and pain in the area of ​​exposure to radiation are possible.

Radiotherapy in the treatment of stomach cancer

Radiation therapy may be included in the treatment plan for stomach cancer, depending on the type of tumor and the extent of the disease.

Radiotherapy is used for the following types of stomach cancer:

• Adenocarcinoma of the stomach
• Stomach lymphoma (eg, MALT or GALT-type lymphoma).

Reasons to do radiation therapy abroad.

In most cases, radiotherapy for gastric adenocarcinoma uses high-tech equipment located outside the patient's body. This treatment is called external (external) radiation therapy. There are several types of external beam radiation therapy, including intensity-modulated radiation therapy (IMRT).

Radiation therapy provides:

• Destruction of malignant cells that could remain in the tissues of the stomach after surgery;
• Shrinking the size of the tumor;
• Pain relief;
• Stopping bleeding;
• Reducing the risk of cancer recurrence in the same area of ​​the body (i.e., in this case, the stomach).

If necessary, radiotherapy is prescribed several months after surgery or chemotherapy, which allows the body to recover adequately. Radiation therapy is painless. During the session, the patient lies on the couch while the linear accelerator generates radiation to act on the tumor. A radiologist (a specialist in radiation therapy) corrects the patient's body position, which makes it possible to target radiation to the malignant tumor, avoiding the maximum possible volume of healthy tissue. Most often, radiotherapy sessions are given 5 days a week for about 5 weeks. Each session only lasts a few minutes. After the session, no radiation remains in the patient's body, so it is completely safe to be with loved ones during the treatment period.

Side effects of radiotherapy for adenocarcinoma, stomach cancer

In the event that radiation therapy for stomach cancer is carried out with the joint use of chemotherapy, then the radiation doses are increased, and the following side effects may develop:

• Nausea (with / without vomiting)
• Diarrhea
• Fatigue
• Stomach pain
• Irritation and darkening of the skin in the area of ​​exposure to radiation.

The use of ionizing radiation for the treatment of malignant neoplasms is based on the damaging effect on cells and tissues, leading to their death when receiving appropriate doses.

Radiation cell death is primarily associated with damage to the DNA nucleus, deoxynucleoproteins and the DNA membrane complex, gross violations in the properties of proteins, cytoplasm, and enzymes. Thus, irradiated cancer cells are disturbed at all levels of metabolic processes. Morphologically, changes in malignant neoplasms can be represented by three sequential stages:

1. damage to the neoplasm;
2. its destruction (necrosis);
3. replacement of dead tissue.

The death of tumor cells and their resorption do not occur immediately. Therefore, the effectiveness of treatment is more accurately assessed only after a certain period of time after its completion.

Radiosensitivity is an intrinsic property of malignant cells. All human organs and tissues are sensitive to ionizing radiation, but their sensitivity is not the same, it changes depending on the state of the body and the action of external factors. The most sensitive to radiation are the hematopoietic tissue, the glandular apparatus of the intestine, the epithelium of the gonads, the skin and the bag of the lens of the eye. Next in terms of the degree of radiosensitivity are endothelium, fibrous tissue, parenchyma of internal organs, cartilage tissue, muscles, and nervous tissue. Some of the neoplasms are listed in order of decreasing radiosensitivity:

• seminoma;
• lymphocytic lymphoma;
• other lymphomas, leukemia, myeloma;
• some embryonic sarcomas, small cell lung cancer, choriocarcinoma;
• Ewing's sarcoma;
• squamous cell carcinoma: highly differentiated, medium degree of differentiation;
• adenocarcinoma of the breast and rectum;
• transitional cell carcinoma;
• hepatoma;
• melanoma;
• glioma, other sarcomas.

The sensitivity of any malignant neoplasm to radiation depends on the specific characteristics of its constituent cells, as well as on the radiosensitivity of the tissue from which the neoplasm originated. The histological structure is an indicative sign of radiosensitivity prediction. Radiosensitivity is influenced by the nature of growth, size and duration of its existence. The radiosensitivity of cells at different stages of the cell cycle is not the same. Cells in the mitotic phase have the highest sensitivity. The greatest resistance is in the synthesis phase. The most radiosensitive neoplasms that originate from tissue characterized by a high rate of cell division, with a low degree of cell differentiation, exophytic growing and well oxygenated. Highly differentiated, large, long-existing tumors with a large number of anoxic cells resistant to radiation are more resistant to ionizing effects.

To determine the amount of absorbed energy, the concept of radiation dose was introduced. Dose is understood as the amount of energy absorbed per unit mass of the irradiated substance. Currently, in accordance with the International System of Units (SI), the absorbed dose is measured in grays (Gy). A single dose is the amount of energy absorbed in one irradiation. Tolerant (tolerated) dose level, or tolerated dose, is the dose at which the incidence of late complications does not exceed 5%. The tolerant (total) dose depends on the irradiation mode and the volume of the irradiated tissue. For connective tissue, this value is assumed to be 60 Gy with an irradiation area of ​​100 cm 2 with a daily irradiation of 2 Gy. The biological effect of radiation is determined not only by the value of the total dose, but also by the time during which it is absorbed.

How is radiation therapy done for cancer?

Radiation therapy for cancer is divided into two main groups: methods of remote and contact radiation.

1. External beam radiation therapy for cancer:
   • static - by open fields, through a lead grid, through a lead wedge-shaped filter, through lead shielding blocks;
   • movable - rotary, pendulum, tangential, rotational-convergent, rotary with controlled speed.
2. Contact radiation therapy for cancer:
   • intracavitary;
   • interstitial;
   • radiosurgical;
   • application;
   • close-focus X-ray therapy;
   • method of selective accumulation of isotopes in tissues.
3. Combined radiation therapy for cancer - a combination of one of the methods of remote and contact radiation.
4. Combined methods of treating malignant neoplasms:
   • radiation therapy for cancer and surgery;
   • radiation therapy for cancer and chemotherapy, hormone therapy.

Radiation therapy for cancer and its effectiveness can be increased by increasing the radiation exposure of the tumor and weakening the reactions of normal tissues. Differences in the radiosensitivity of neoplasms and normal tissues are called the radiotherapy interval (the higher the therapeutic interval, the greater the dose of radiation can be delivered to the tumor). To increase the latter, there are several ways to selectively control tissue radiosensitivity.

• Variations in dose, rhythm and time of exposure.
• The use of the radio-modifying action of oxygen - by selectively increasing the radiosensitivity of the neoplasm, its oxygenation and by reducing the radiosensitivity of normal tissues by creating short-term hypoxia in them.
• Tumor radiosensitization with some chemotherapy drugs.

Many anticancer drugs act on dividing cells that are in a specific phase of the cell cycle. At the same time, in addition to the direct toxic effect on DNA, they slow down the repair processes and delay the passage of a particular phase by the cell. In the phase of mitosis, which is most sensitive to radiation, the cell is retained by vinca alkaloids and taxanes. Hydroxyurea inhibits the cycle in the G1 phase, which is more sensitive to this type of treatment compared to the synthesis phase, 5-fluorouracil in the S-phase. As a result, a greater number of cells enter the mitosis phase at the same time, and due to this, the damaging effect of radioactive radiation is enhanced. Drugs such as platinum, when combined with ionizing effects, inhibit the restoration of damage to malignant cells.

• Selective local tumor hyperthermia causes disruption of post-radiation recovery processes. The combination of radioactive irradiation with hyperthermia makes it possible to improve the results of treatment in comparison with the independent effect on the neoplasm of each of these methods. This combination is used in the treatment of patients with melanoma, rectal cancer, breast cancer, head and neck tumors, bone and soft tissue sarcomas.
• Creation of short-term artificial hyperglycemia. A decrease in pH in tumor cells leads to an increase in their radiosensitivity due to disruption of the processes of post-radiation recovery in an acidic environment. Therefore, hyperglycemia causes a significant increase in the antitumor effect of ionizing radiation.

An important role in increasing the effectiveness of such a method of treatment as radiation therapy for cancer is played by the use of non-ionizing radiation (laser radiation, ultrasound, magnetic and electric fields).

In oncological practice, radiation therapy for cancer is used not only as an independent method of radical, palliative treatment, but also much more often as a component of combined and complex treatment (various combinations with chemotherapy, immunotherapy, surgical and hormonal treatment).

Radiation therapy for cancer alone and in combination with chemotherapy is most often used for cancer of the following localizations:

• Cervix;
• leather;
• larynx;
• upper esophagus;
• malignant neoplasms of the oral cavity and pharynx;
• non-Hodgkin's lymphomas and lymphogranulomatosis;
• inoperable lung cancer;
• Ewing's sarcoma and reticulosarcoma.

Depending on the sequence of application of ionizing radiation and surgical interventions, pre-, post- and intraoperative methods of treatment are distinguished.

Preoperative radiation therapy for cancer

Depending on the purposes for which it is assigned, there are three main forms:

• irradiation of operable forms of malignant neoplasms;
• irradiation of inoperable or doubtfully resectable tumors;
• irradiation with delayed selective surgery.

When irradiating the zones of clinical and subclinical spread of the tumor before surgery, lethal damage is first achieved for the most highly malignant proliferating cells, most of which are located in the well-oxygenated peripheral areas of the neoplasm, in the zones of its growth both in the primary focus and in metastases. Lethal and sublethal damage are also received by non-multiplying complexes of cancer cells, due to which their ability to engraft is reduced if they enter the wound, blood and lymph vessels. The death of tumor cells as a result of ionizing exposure leads to a decrease in the size of the tumor, delimiting it from the surrounding normal tissues due to the proliferation of connective tissue elements.

These changes in tumors are realized only when the optimal focal dose of radiation is used in the preoperative period:

• the dose should be sufficient to cause the death of most of the tumor cells;
• should not cause noticeable changes in normal tissues leading to impaired healing of postoperative wounds and an increase in postoperative mortality.

Currently, two methods of preoperative remote irradiation are most often used:

• daily irradiation of the primary tumor and regional zones at a dose of 2 Gy to a total focal dose of 40 - 45 Gy for 4 - 4.5 weeks of treatment;
• irradiation of similar volumes at a dose of 4 - 5 Gy for 4 - 5 days to a total focal dose of 20 - 25 Gy.

In the case of using the first technique, the operation is usually performed 2–3 weeks after the end of the irradiation, and when using the second, after 1–3 days. The latter technique can be recommended only for the treatment of patients with resectable malignant tumors.

Postoperative radiation therapy for cancer

It is prescribed for the following purposes:

• "Sterilization" of the operating field from malignant cells and their complexes scattered during the operation;
• complete removal of the remaining malignant tissue after incomplete removal of the tumor and metastases.

Postoperative radiation therapy for cancer is usually done for cancers of the breast, esophagus, thyroid gland, uterus, fallopian tubes, vulva, ovaries, kidney, bladder, skin and lip, more common head and neck cancers, salivary gland tumors, cancer rectum and colon, tumors of the endocrine organs. Although many of these tumors are not radiosensitive, this type of treatment can destroy the remnants of the tumor after surgery. At present, the use of organ-preserving operations is expanding, especially in cancer of the breast, salivary glands and rectum, while radical postoperative ionizing treatment is required.

It is advisable to start treatment no earlier than 2 - 3 weeks after surgery, i.e. after the wound has healed and the inflammatory changes in normal tissues have subsided.

To achieve a therapeutic effect, it is necessary to administer high doses - at least 50-60 Gy, and it is advisable to increase the focal dose to the area of ​​unremoved tumor or metastases to 65 - 70 Gy.

In the postoperative period, it is necessary to irradiate the areas of regional tumor metastasis in which no surgical intervention was performed (for example, supraclavicular and parasternal lymph nodes in breast cancer, iliac and para-aortic nodes in uterine cancer, para-aortic nodes in testicular seminoma). Radiation doses can be in the range of 45 - 50 Gy. To preserve normal tissues, radiation after surgery should be carried out using the method of classical dose fractionation - 2 Gy per day or in average fractions (3.0 - 3.5 Gy) with the addition of a daily dose for 2 - 3 fractions with an interval of 4 - 5 hours between them. ...

Intraoperative radiation therapy for cancer

In recent years, there has been renewed interest in the use of remote megavolt and interstitial irradiation of a tumor or its bed. The advantages of this type of irradiation are the ability to visualize the tumor and the irradiation field, remove normal tissues from the irradiation zone, and implement the features of the physical distribution of fast electrons in tissues.

This radiation therapy for cancer is used for the following purposes:

• irradiation of the tumor before its removal;
• irradiation of the tumor bed after radical surgery or irradiation of residual tumor tissue after non-radical surgery;
• irradiation of an unresectable tumor.

A single dose of radiation to the area of ​​the tumor bed or surgical wound is 15 - 20 Gy (a dose of 13 + 1 Gy is equivalent to a dose of 40 Gy, administered 5 times a week at 2 Gy), which does not affect the course of the postoperative period and causes the death of most subclinical metastases and radiosensitive tumor cells that may disseminate during surgery.

With radical treatment, the main task is to completely destroy the tumor and cure the disease. Radiation therapy for cancer consists of a therapeutic ionizing effect on the area of ​​clinical tumor spread and prophylactic irradiation of areas of possible subclinical damage. Radiation therapy for cancer, carried out mainly for a radical purpose, is used in the following cases:

• mammary cancer;
• cancer of the mouth and lips, pharynx, larynx;
• cancer of the female genital organs;
• skin cancer;
• lymphomas;
• primary brain tumors;
• prostate cancer;
• unresectable sarcomas.

Complete removal of the tumor is most often possible in the early stages of the disease, with a small tumor with high radiosensitivity, without metastases, or with single metastases to the nearest regional lymph nodes.

Palliative radiation therapy for cancer is used to minimize biological activity, inhibit growth, and reduce tumor size.

Radiation therapy for cancer, carried out mainly for palliative purposes, is used in the following cases:

• bone and brain metastases;
• chronic bleeding;
• esophageal carcinoma;
• lung cancer;
• to reduce increased intracranial pressure.

At the same time, severe clinical symptoms are reduced.

1. Pain (pain in the bones with metastases of breast, bronchial or prostate cancer respond well to short courses).
2. Obstruction (for esophageal stenosis, atelectasis of the lung or compression of the superior vena cava, for lung cancer, compression of the ureter for cancer of the cervix or bladder, palliative radiation therapy is often beneficial).
3. Bleeding (causes great concern and is usually seen in advanced cancers of the cervix and body of the uterus, bladder, pharynx, bronchi and oral cavity).
4. Ulceration (radiation therapy can reduce ulceration in the chest wall in breast cancer, in the perineum in rectal cancer, eliminate foul odor and thus improve quality of life).
5. Pathological fracture (irradiation of large foci in the supporting bones, both of a metastatic nature and primary in Ewing's sarcoma and myeloma, can prevent a fracture; in the presence of a fracture, treatment should be preceded by fixation of the affected bone).
6. Relief of neurological disorders (metastases of breast cancer to retrobulbar tissue or retina regress under the influence of this type of treatment, which usually also preserves vision).
7. Relief of systemic symptoms (myasthenia gravis due to a tumor of the thymus gland responds well to irradiation of the gland).

When is radiation therapy for cancer contraindicated?

Radiation therapy for cancer is not carried out with a severe general condition of the patient, anemia (hemoglobin below 40%), leukopenia (less than 3-109 / l), thrombocytopenia (less than 109 / l), cachexia, intercurrent diseases accompanied by a febrile state. Radiation therapy is contraindicated for cancer with active pulmonary tuberculosis, acute myocardial infarction, acute and chronic hepatic and renal failure, pregnancy, severe reactions. Because of the risk of bleeding or perforation, this type of treatment is not given for disintegrating tumors; not prescribed for multiple metastases, serous effusion in the cavity and severe inflammatory reactions.

Radiation therapy for cancer can be accompanied by the occurrence of both forced, inevitable or acceptable, and unacceptable unexpected changes in healthy organs and tissues. These changes are based on damage to cells, organs, tissues and body systems, the degree of which mainly depends on the dose.

Damage according to the severity of the course and the time of their relief are subdivided into reactions and complications.

Reactions - changes that occur in organs and tissues at the end of the course, passing independently or under the influence of appropriate treatment. They can be local and general.

Complications - persistent, difficult to eliminate or permanently remaining disorders caused by tissue necrosis and their replacement with connective tissue, do not go away on their own, require long-term treatment.

Radiation Oncology (Interventional Radiology)- a field of medicine in which the use of ionizing radiation for the treatment of oncological diseases is being investigated. In general terms, the method can be described as follows. Corpuscular or wave radiation is directed to the area of ​​the body affected by the tumor in order to remove malignant cells with minimal damage to the surrounding healthy tissue. Radiation is one of the three main methods of fighting cancer, along with surgery and chemotherapy.

Classification of methods of radiation oncology

First, the different types of radiation should be distinguished.

• α-particles,
• proton beams,
• β-particles,
• electron beams,
• π-mesons,
• neutron radiation.

• γ-radiation,
• bremsstrahlung x-ray radiation.

Secondly, there are various ways to summarize it.

• Contact therapy... With this method, the emitter is brought directly to the tumor. In most cases, surgical intervention is required for implementation, so the method is rarely used.
• Interstitial method... Radioactive particles are injected into the tissue containing the tumor. As an independent treatment, it is mainly used for gynecological and oncological diseases. As an additional one - with external (remote) irradiation.

Currently, the field of application of brachytherapy as an independent or auxiliary method is expanding, new methods are emerging, for example, SIRT therapy.

External (remote) exposure :

With this effect, the emitter is located at a distance from the area containing the malignant formation. The method is the most versatile, however, and the most difficult to implement. The development of this area of ​​oncology is closely related to scientific and technological progress. The first significant advances are associated with the invention and introduction of cobalt radiotherapy (1950s). The next stage was marked by the creation of a linear accelerator. Further development is due to the introduction of computer technologies and various modulation methods (changes in beam characteristics). Many innovations have been made in this direction, including:

• three-dimensional conformal radiation therapy (3DCRT),
• intensity modulated radiation therapy (IMRT),
• the emergence of radiosurgery (the use of narrow beams of high intensity),
• technologies that combine the use of 3D / 4D modeling and intensity modulation (for example, RapidArc).

Modern installations for conducting radiotherapy are the most complex and expensive devices that combine engineering achievements from many technological fields. Today, two areas of remote irradiation can be distinguished.

• Radiation therapy . From the very beginning, radiation oncology has developed in this direction: radiation therapy involves the use of wide beams of ionizing radiation. Traditional RT is usually performed in several sessions. Now there are many implementations of this approach: the irradiation technique is constantly being improved and has undergone many changes over time. RT is now one of the most common cancer treatments. It is used for many types of tumors and stages: either as an independent method of therapy, or in combination with others (for example, radiochemotherapy). RT is also used for palliative purposes.
• Radiosurgery. A relatively new area of ​​interventional radiology, which is characterized by the use of highly targeted radiation of increased intensity. The procedure takes place in fewer sessions in comparison with RT. So far, the area of ​​applicability of radiosurgery is limited and small compared to radiation therapy. However, the direction is actively developing and progressing. The most popular settings: Cyber ​​Knife and its predecessors Gamma Knife, LINAC.

Exposure to radiation

The processes that occur in cells under irradiation are extremely complex; numerous morphological and functional changes in tissues occur. The beginning of these processes is the ionization and excitation of the atoms and molecules that make up the cells. We do not intend to describe these processes in detail, therefore, we will give only a few examples.

The positive effect of radiation consists in disrupting the processes of self-regulation in malignant cells, which, over time, leads to their death. As a result of the destruction of the DNA structure of cancer cells, they lose their ability to divide. Irradiation destroys the vessels of the tumor, disrupts its nutrition.

The negative effect is that changes can also occur in healthy cells. This leads to radiation complications, which are divided into two groups.

• Radiation reactions... Violations are temporary and disappear after a certain time (up to several weeks).
• Radiation damage... Irreversible effects of radiation.

Each type of cells has its own indicators of radiosensitivity, that is, changes in cells begin at a certain ratio of frequency, type, intensity and duration of radiation. In principle, any tumor can be destroyed by exposure to radiation, but healthy cells will also be damaged. The main task of rational oncology is to find the optimal balance between the beneficial effect of radiation and minimizing the risk of complications.

In more detail, the most typical side effects and features of the radiation are considered for specific types of oncological diseases to which radiation therapy is applicable. See the following materials

Minimizing complications

Since the inception of the field, radiation oncology has evolved towards minimizing side effects. On this path, many innovations have been developed. Let's consider the main techniques that are used by specialists to reduce the risk of damage to healthy tissue.

X-ray range

High-intensity X-ray radiation allows you to act on deep tissues, while slightly damaging the surface ones: the beam passes through the skin, almost without losing energy on it. By selecting the optimal intensity, the area of ​​the main effect is transferred to the required depth, as a result, healthy cells receive a small dose of radiation, and the likelihood of getting a burn on the skin disappears.

Currently, X-ray is used in the absolute majority of installations, but this is not the only type of radiation used in interventional radiology: broad prospects are opened, for example, by proton therapy.

Accurate approach

The primary task is to accurately determine the location of the tumor. Often it is necessary to remove not a clearly isolated neoplasm, but the remnants of the tumor after the operation, possible foci of metastasis, which can be multiple, difficult to notice and have an irregular arrangement. To determine their location, all available means are used: MRI, computed tomography, PET-CT, the protocol of the operation performed. It also requires reliable knowledge about the properties of the surrounding tissue: it is necessary to determine where new tumor foci can form and prevent this process.

Today, the use of a computer model of the tumor process has become the gold standard for radiotherapy and radiosurgery: the radiation strategy is calculated using such models. Cyberknife, for example, uses supercomputer computation for this.

Considerable efforts are also directed at maintaining the final irradiation accuracy: the patient's actual position may differ from the one in which the model was constructed, therefore either methods of reconstructing the position or correcting the irradiation direction are required.

• Commit methods... Often, radiation therapy lasts 30-40 courses, and it is necessary to maintain an accuracy within half a centimeter. For these purposes, various methods of fixing the position of the patient are used.
• Respiratory control... Irradiation of movable organs is a significant complication: at present, several techniques have been developed that make it possible to monitor the patient's breathing and either correct the direction of exposure or suspend it until it returns to the permissible range of positions.

Irradiation at different angles

With the exception of rare cases when changing the angle at which the beam is directed is impossible, this method must be applied. This technique allows you to evenly distribute side effects and reduce the total dose per unit volume of healthy tissue. Most of the installations can rotate the linear accelerator in a circle (2D rotation), some installations also allow spatial rotations / displacements (not only along one axis).

Fractionation

It is necessary to determine as accurately as possible the properties of healthy and cancerous cells that are affected and to identify differences in radiosensitivity. The intensity and type of communication are selected individually for each case, thanks to which it is possible to optimize the effectiveness of therapy.

Modulation

In addition to the direction of exposure, the beam has two important cross-sectional characteristics: shape and intensity distribution. By changing the shape of the beam, it is possible to prevent exposure to healthy organs with high radiosensitivity. Due to the distribution of intensity - to reduce the dose of radiation for the tissues bordering with the tumor and, conversely, to increase it for the tumor focus.

Similar techniques have been used since the 90s. when the intensity modulation technology was invented. At first, the devices allowed the use of only several (1-7) directions of irradiation (for each of which the optimal beam characteristics were calculated in advance) during one session. Now appeared multi-leaf collimators(a device that forms the shape of the beam) that can quickly recreate different profiles, keeping up with the rotation of the linear accelerator. Thanks to this, it became possible to produce irradiation in an unlimited number of directions during one session (RapidArc technology), which makes it possible to shorten the duration of therapy by almost an order of magnitude.